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Abstract:

A battery charging system and a charging method thereof for a hybrid
construction machine using a rotating force of a fan are disclosed. The
battery charging system includes a fan, a controller controlling a
braking device of the fan and a battery which is charged with electric
energy. The charging method includes controlling, by the controller, a
braking device of the fan to decrease a fan rotating speed down to a
target fan rotating speed if the current target fan rotating speed, which
is obtained depending on a current cooling water temperature, a hydraulic
fluid temperature, and an engine intake air temperature, is lower than an
actually measured fan rotating speed; and charging, by the braking
device, electric energy which is caused by a rotating force that is
generated while the fan rotating speed is decreased from the actually
measured fan rotating speed to the target fan rotating speed in the
battery. Since the electric energy generated by the rotating force is
stored in the battery, the engine operation time is reduced, and thus a
fuel efficiency can be improved.

Claims:

1. A charging method of a battery charging system for a hybrid
construction machine using a rotating force of a fan, including the fan,
a controller controlling a braking device of the fan, and a battery
charged with electric energy, comprising: Controlling, by the controller,
the braking device to decrease a fan rotating speed down to a target fan
rotating speed if the current target fan rotating speed, which is
obtained depending on a current cooling water temperature, a hydraulic
fluid temperature, and an engine intake air temperature, is lower than an
actually measured fan rotating speed; and charging, by the braking
device, the electric energy, which is caused by a rotating force that is
generated while the fan rotating speed is decreased from the actually
measured fan rotating speed to the target fan rotating speed, in the
battery.

2. The charging method according to claim 1, wherein the step of
controlling the braking device comprises: Obtaining, by the controller,
the current target fan rotating speed depending on the current cooling
water temperature, the hydraulic fluid temperature, and the engine intake
air temperature using the target fan rotating speed that is differently
set according to the current cooling water temperature, the hydraulic
fluid temperature, and the engine intake air temperature; comparing the
currently obtained target fan rotating speed with the actually measured
fan rotating speed; and outputting a first control signal for increasing
the fan rotating speed up to the target fan rotating speed to the fan if
the target fan rotating speed is higher than the actually measured fan
rotating speed as the result of the comparison, and outputting a second
control signal for decreasing the fan rotating speed down to the target
fan rotating speed to the braking device if the target fan rotating speed
is lower than the actually measured fan rotating speed as the result of
the comparison.

3. A battery charging system for a hybrid construction machine using a
rotating force of a fan, comprising: a speed measurement means for
measuring an actual fan rotating speed during measurement; a controller
outputting a control signal for decreasing the fan rotating speed down to
a target fan rotating speed if the current target fan rotating speed,
which is obtained depending on a current cooling water temperature, a
hydraulic fluid temperature, and an engine intake air temperature, is
lower than an actually measured fan rotating speed that is measured by
the speed measurement means; a braking device of the fan braking a fan
rotating operation under the control of the controller; and a battery
charged with electric energy which is caused by a rotating force that is
generated while the fan rotating speed is decreased from the actually
measured fan rotating speed to the target fan rotating speed by the
braking device.

4. The battery charging system according to claim 3, wherein the
controller obtains the current target fan rotating speed depending on the
current cooling water temperature, the hydraulic fluid temperature, and
the engine intake air temperature using the target fan rotating speed
that is differently set according to the current cooling water
temperature, the hydraulic fluid temperature, and the engine intake air
temperature; compares the currently obtained target fan rotating speed
with the actually measured fan rotating speed; and outputs a first
control signal for increasing the fan rotating speed up to the target fan
rotating speed to the fan if the target fan rotating speed is higher than
the actually measured fan rotating speed as the result of the comparison,
while outputting a second control signal for decreasing the fan rotating
speed down to the target fan rotating speed to the braking device if the
target fan rotating speed is lower than the actually measured fan
rotating speed as the result of the comparison.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a battery charging system and a
charging method thereof for a hybrid construction machine using a
rotating force of a fan. More particularly, the present invention relates
to a battery charging system and a charging method thereof for a hybrid
construction machine using a rotating force of a fan, which can reduce an
engine operating time through storing of electric energy that is
generated by the rotating force of the fan in a battery, and thus can
improve fuel efficiency.

BACKGROUND ART

[0002] In general, Korean patent publication "KR1020110084960A Working
machine" discloses a hybrid construction machine as a working machine,
which includes a DC bus connected to a swing motor through an inverter
circuit, a battery connected to the DC bus through a booster converter
and a switch, a controller driving the inverter circuit and the booster
converter, a coolant circulation system including a pump motor, and the
inverter circuit connected to the DC bus to drive the pump motor.

[0003] The controller has a mode for lowering a voltage of the DC bus, and
in the mode, the controller operates the inverter circuit to make the
pump motor consume a power after making the switch in a non-contact
state.

[0004] However, in the above-described technology in the related art, a
cooling fan that is fixed to a typical engine crank shaft is rotated in
proportion to an engine rpm regardless of the temperature of cooling
water.

[0005] As a result, in the case where the engine rpm is high even if the
temperature of the cooling water is low, the rotating speed of the fan
becomes high, and thus the fan is rotated at high speed to cause
inefficiency of the fan.

DISCLOSURE

Technical Problem

[0006] Therefore, the present invention has been made to solve the
above-mentioned problems occurring in the related art, and an object of
the present invention is to provide a battery charting system and a
charging method thereof for a hybrid construction machine using a
rotating force of a fan, which can provide an energy recovery system that
is useful to a charging system of a hybrid system by generating a larger
amount of electric energy through compulsory reduction of the rotating
speed of a fan using a braking device and a controller mounted thereon
and storing the electric energy that is generated during the rotation in
a battery in the case where a temperature of cooling water is low.

Technical Solution

[0007] In accordance with an aspect of the present invention, there is
provided a charging method of a battery charging system for a hybrid
construction machine using a rotating force of a fan, including the fan,
a controller controlling a braking device of the fan, and a battery
charged with electric energy, which includes controlling, by the
controller, the braking device to decrease a fan rotating speed down to a
target fan rotating speed if the current target fan rotating speed, which
is obtained depending on a current cooling water temperature, a hydraulic
fluid temperature, and an engine intake air temperature, is lower than an
actually measured fan rotating speed; and charging, by the braking
device, the electric energy, which is caused by a rotating force that is
generated while the fan rotating speed is decreased from the actually
measured fan rotating speed to the target fan rotating speed, in the
battery.

[0008] Preferably, the step of controlling the braking device includes
obtaining, by the controller, the current target fan rotating speed
depending on the current cooling water temperature, the hydraulic fluid
temperature, and the engine intake air temperature using the target fan
rotating speed that is differently set according to the current cooling
water temperature, the hydraulic fluid temperature, and the engine intake
air temperature; comparing the currently obtained target fan rotating
speed with the actually measured fan rotating speed; and outputting a
first control signal for increasing the fan rotating speed up to the
target fan rotating speed to the fan if the target fan rotating speed is
higher than the actually measured fan rotating speed as the result of the
comparison, and outputting a second control signal for decreasing the fan
rotating speed down to the target fan rotating speed to the braking
device if the target fan rotating speed is lower than the actually
measured fan rotating speed as the result of the comparison.

[0009] In accordance with another aspect of the present invention, there
is provided a battery charging system for a hybrid construction machine
using a rotating force of a fan, which includes a speed measurement means
for measuring an actual fan rotating speed during measurement; a
controller outputting a control signal for decreasing the fan rotating
speed down to a target fan rotating speed if the current target fan
rotating speed, which is obtained depending on a current cooling water
temperature, a hydraulic fluid temperature, and an engine intake air
temperature, is lower than an actually measured fan rotating speed that
is measured by the speed measurement means; a braking device of the fan
braking a fan rotating operation under the control of the controller; and
a battery charged with electric energy which is caused by a rotating
force that is generated while the fan rotating speed is decreased from
the actually measured fan rotating speed to the target fan rotating speed
by the braking device.

[0010] Preferably, the controller obtains the current target fan rotating
speed depending on the current cooling water temperature, the hydraulic
fluid temperature, and the engine intake air temperature using the target
fan rotating speed that is differently set according to the current
cooling water temperature, the hydraulic fluid temperature, and the
engine intake air temperature; compares the currently obtained target fan
rotating speed with the actually measured fan rotating speed; and outputs
a first control signal for increasing the fan rotating speed up to the
target fan rotating speed to the fan if the target fan rotating speed is
higher than the actually measured fan rotating speed as the result of the
comparison, while outputting a second control signal for decreasing the
fan rotating speed down to the target fan rotating speed to the braking
device if the target fan rotating speed is lower than the actually
measured fan rotating speed as the result of the comparison.

Advantageous Effect

[0011] Since the battery charting system according to the present
invention stores the electric energy that is generated by the rotating
operation of the cooling fan in the battery, the additional energy that
is generated according to the hybrid concept and is stored in the battery
can be used to reduce the engine operation time, and thus the fuel
efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above objects, other features and advantages of the present
invention will become more apparent by describing the preferred
embodiments thereof with reference to the accompanying drawings, in
which:

[0013] FIG. 1 is a block diagram illustrating the configuration of the
battery charging system for a hybrid construction machine using a
rotating force of a fan according to an embodiment of the present
invention;

[0014] FIG. 2 is a flowchart sequentially illustrating the operation of a
battery charging system for a hybrid construction machine using a
rotating force of a fan according to the present invention; and

[0015] FIG. 3 is a diagram illustrating an example of a battery charging
system for a hybrid construction machine according to the present
invention.

BEST MODE

[0016] Hereinafter, preferred embodiments of the present invention will be
described in detail with reference to the accompanying drawings.

[0017] The matters defined in the description, such as the detailed
construction and elements, are nothing but specific details provided to
assist those of ordinary skill in the art in a comprehensive
understanding of the invention, and the present invention is not limited
to the embodiments disclosed hereinafter.

[0018] For clear explanation of the present invention, portions that do
not have relation to the explanation are omitted, and in the entire
description of the present invention, similar drawing reference numerals
are used for the similar elements across various figures.

[0019] In the entire description and claims of the present invention, the
term "comprises" and/or "includes" used in the description means that one
or more other components are not excluded in addition to the described
components unless specially described on the contrary.

[0020] FIG. 1 is a block diagram illustrating the configuration of the
battery charging system for a hybrid construction machine using a
rotating force of a fan according to an embodiment of the present
invention.

[0021] As illustrated in FIG. 1, the battery charging system according to
the present invention is configured to include a plurality of temperature
sensors 101 to 103, a speed measurement means (e.g., tachometer) 104, a
fan 105, a controller 106, a braking device 107, and a battery 108.

[0022] Here, the plurality of temperature sensors 101 to 103 include a
first temperature sensor 101 sensing a cooling water temperature, a
second temperature sensor 102 sensing a hydraulic fluid temperature, and
a third temperature sensor 103 sensing an engine intake air temperature.
The controller 106 obtains the current target fan rotating speed using
information on the cooling water temperature, the hydraulic fluid
temperature, and the engine intake air temperature sensed by the
respective temperature sensors 101 to 103.

[0023] The speed measurement means 104 is electrically connected to the
controller, and measures and inputs the current fan rotating speed to the
controller connected thereto. For example, a tachometer may be used. The
current fan rotating speed that is input to the controller is used to
determine a control signal to be output.

[0024] The fan 105 may be a cooling fan that is fixed to an engine crank
shaft. If the cooling water temperature is low, the rotating speed is
compulsorily decreased by the braking device, and thus a larger amount of
electric energy can be generated. The generated electric energy is stored
in the battery.

[0025] The controller 106 outputs a control signal for decreasing the fan
rotating speed down to a target fan rotating speed if the current target
fan rotating speed, which is obtained depending on the current cooling
water temperature, the hydraulic fluid temperature, and the engine intake
air temperature, is lower than the actually measured fan rotating speed
that is measured by the speed measurement means 104. That is, the
controller obtains the current target fan rotating speed depending on the
current cooling water temperature, the hydraulic fluid temperature, and
the engine intake air temperature using the target fan rotating speed
that is differently set according to the current cooling water
temperature, the hydraulic fluid temperature, and the engine intake air
temperature. Then, the controller compares the currently obtained target
fan rotating speed with the actually measured fan rotating speed, and
outputs a first control signal for increasing the fan rotating speed up
to the target fan rotating speed to the fan 105 if the target fan
rotating speed is higher than the actually measured fan rotating speed as
the result of the comparison, while outputting a second control signal
for decreasing the fan rotating speed down to the target fan rotating
speed to the braking device 107 if the target fan rotating speed is lower
than the actually measured fan rotating speed as the result of the
comparison.

[0026] The braking device (e.g., clutch) 107 brakes a fan rotating
operation under the control of the controller 106.

[0027] The battery 108 is charged with electric energy which is caused by
a rotating force that is generated while the fan rotating speed is
decreased from the actually measured fan rotating speed to the target fan
rotating speed by the braking device 107. That is, in the case of a
cooling fan that is fixed to the engine crank shaft, the fan is rotated
in proportion to an engine rpm regardless of the cooling water
temperature. In the case where the engine rpm is high even if the
temperature of the cooling water is low, the rotating speed of the fan
becomes high, and thus the fan is rotated at high speed to cause
inefficiency of the fan. However, according to the present invention, the
braking device and the controller are mounted, and a larger amount of
electric energy can be generated through compulsory reduction of the
rotating speed of the fan using the braking device, and the electric
energy that is generated at that time can be stored in the battery in the
case where the cooling water temperature is low. Accordingly, the battery
is useful to the charging system of the hybrid system.

[0028] Hereinafter, the operation of the battery charging system for a
hybrid construction machine using the rotating force of the fan according
to the present invention illustrated in FIG. 1 will be described with
reference to FIG. 2.

[0029] FIG. 2 is a flowchart sequentially illustrating the operation of a
battery charging system for a hybrid construction machine using a
rotating force of a fan according to the present invention.

[0030] As illustrated in FIG. 2, according to the charging method
according to the present invention, a plurality of temperature sensors
101 to 103 respectively sense a current cooling water temperature, a
hydraulic fluid temperature, and an engine intake air temperature (S201
to S203).

[0032] Next, a controller 106 outputs a control signal for decreasing the
fan rotating speed down to a target fan rotating speed if the current
target fan rotating speed, which is obtained depending on the current
cooling water temperature, the hydraulic fluid temperature, and the
engine intake air temperature, is lower than the actually measured fan
rotating speed that is measured by the speed measurement means 104.

[0033] Specifically, the controller obtains the current target fan
rotating speed depending on the current cooling water temperature, the
hydraulic fluid temperature, and the engine intake air temperature that
are input from the temperature sensors 101 to 103 using the target fan
rotating speed that is differently set according to the current cooling
water temperature, the hydraulic fluid temperature, and the engine intake
air temperature (S204).

[0035] If the target fan rotating speed is higher than the actually
measured fan rotating speed as the result of the comparison, the
controller outputs a first control signal for increasing the fan rotating
speed up to the target fan rotating speed to the fan 105 (S206 to S207).

[0036] In contrast, if the target fan rotating speed is lower than the
actually measured fan rotating speed as the result of the comparison, the
controller outputs a second control signal for decreasing the fan
rotating speed down to the target fan rotating speed to the braking
device 107 (S208).

[0037] Then, a braking device (e.g., clutch) 107 brakes the fan rotating
operation under the control of the controller 106 (S209).

[0038] In this case, the rotating force is generated while the fan
rotating speed is decreased from the actually measured fan rotating speed
to the target fan rotating speed by the braking device 107, and the
electric energy that is generated by the rotating force is charged in a
battery 108 (S210).

[0039] That is, through the above-described control, the electric energy,
which is caused by the rotating force that is generated while the fan
rotating speed is decreased from the actually measured fan rotating speed
to the target fan rotating speed by the braking device 107, is charged in
the battery 108.

[0040] For example, in the case of the cooling fan that is fixed to the
engine crank shaft, the fan is rotated in proportion to the engine rpm
regardless of the cooling water temperature. In the case where the engine
rpm is high even if the temperature of the cooling water is low, the
rotating speed of the fan becomes high, and thus the fan is rotated at
high speed to cause inefficiency of the fan. However, according to the
present invention, the braking device and the controller are mounted, and
a larger amount of electric energy can be generated through compulsory
reduction of the rotating speed of the fan using the braking device, and
the electric energy that is generated at that time can be stored in the
battery in the case where the cooling water temperature is low.
Accordingly, the battery is useful to the charging system of the hybrid
system.

[0041] As described above, according to the present invention, the braking
device and the controller are mounted, and a larger amount of electric
energy can be generated through compulsory reduction of the rotating
speed of the fan using the braking device, and the electric energy that
is generated at that time can be stored in the battery in the case where
the cooling water temperature is low. Accordingly, the engine operating
time can be reduced, and the fuel efficiency can be improved.

[0042] FIG. 3 is a diagram illustrating an example of a battery charging
system for a hybrid construction machine according to the present
invention.

[0043] As illustrated in FIG. 3, the battery charging system according to
the present invention includes a specific fan, a controller controlling a
braking device (a clutch C and a brake system B in the drawing) of the
fan, and a battery charged with electric energy.

[0044] Here, in the case where the current target fan rotating speed that
is obtained depending on the current cooling water temperature, the
hydraulic fluid temperature, and the engine intake air temperature is
lower than the actually measured fan rotating speed, the controller
controls the braking device (the clutch C and the brake system B in the
drawing) to decrease the fan rotating speed down to the target rotating
speed.

[0045] Further, through the above-described control, the electric energy,
which is caused by the rotating force that is generated while the fan
rotating speed is decreased from the actually measured fan rotating speed
to the target fan rotating speed by the braking device, is charged in the
battery.

[0046] On the other hand, through the control of the braking device, the
current target fan rotating speed is obtained depending on the current
cooling water temperature, the hydraulic fluid temperature, and the
engine intake air temperature using the target fan rotating speed that is
differently set by the controller according to the cooling water
temperature, the hydraulic fluid temperature, and the engine intake air
temperature.

[0047] Then, the obtained current target rotating speed and the actually
measured fan rotating speed are compared with each other.

[0048] If the target fan rotating speed is higher than the actually
measured fan rotating speed as the result of the comparison, a first
control signal for increasing the fan rotating speed up to the target fan
rotating speed is output to the fan.

[0049] On the other hand, if the target fan rotating speed is lower than
the actually measured fan rotating speed as the result of the comparison,
a second control signal for decreasing the fan rotating speed down to the
target fan rotating speed is output to the braking device.

[0050] For reference, a tachometer T that is a speed measurement means is
used to measure the current fan rotating speed.

INDUSTRIAL APPLICABILITY

[0051] As apparent from the above description, the present invention can
be used in a battery charging system and a charging method thereof for a
hybrid construction machine using a rotating force of a fan, which can
reduce an engine operating time through storing of electric energy that
is generated by the rotating force of the fan in a battery, and thus can
improve fuel efficiency.